The present invention generally relates to an electrophotographic apparatus, and more particularly to an electrophotographic apparatus which uses an electrophotographic process, such as a laser beam printer, a laser beam copying machine or a laser beam facsimile machine. More particularly, the pesent invention is directed to a replaceable unit determination mechanism capable of determining whether or not a replaceable unit is placed in position and determining whether or not the replaceable unit is a new one.
An electrophotographic apparatus includes a photosensitive member, a developer, a cleaning device and a fixing device. There is a need to replace these elements at regular intervals with new ones. Conventionally, the elements are formed as replaceable "units". There is a possibility that the electrophotographic apparatus is mistakenly driven without placing a unit in position. In this case, toner particles may be scattered in the apparatus, or paper may be transported out of position. There is also a possibility that a used unit is mistakenly placed in position instead of placing a new unit.